Process for recovering nicotine from tobacco



h; B. ARNOLD PROCESS FOR RECOVERING NICOTINE FROM TOBACCO i J N Y L] T Jl h F i; 42

i g l W WvW nicotine is first released alkali to the tobacco, the.function of which Patented May 19, 1925.

UNITED STATES I 1,538,265 PATENT OFFICE.

ROBERT B. ARNOLD, 0! 8T. LOUIS QIISSOUBI, ASSIGNOR TO HALL TOBACCOCHEMICAL COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

PROCESS FOR BECOVERIIQG NICOTINE FROM TOBACCO.

Appllcationfled February 21, Serial No. 535,250.

To (1U whom it may conaem-:

Be it known that I, ROBERT B. ARNOLD, a citizen of the United States,and resident of St. Louis, in the county of St'. Louis and State ofMissouri, have invented certain new and useful Improvements in Processesfor Recovering Nicotine from Tobacco, of which the following is aspecification.

My invention relates generally to the recovery of nicotine from tobacco,and is especially directed to an improved process for extractingnicotine from waste tobacco, leaving a residue suitable for use asfertilizer.

My process is of the type in which the is to combine withthe acidsubstances holdmg the nicotine; and the latter is then extracted invapor form whichcarries off a certain amount of nicotine vapor attemperatures well below the boiling point of nicotine. Morespecifically, my invention pertains to a process of this kind in whichwater is applied directly to the tobacco, and is then turned to vapor bysuitable heating means. I

.My improved process is in general designed to increase the cfliciencyand decrease the cost of this type of process. To this end, oneimportant object is to decrease substantially the amount of heatingnecessary while obtaining a satisfactory yield of nicotine, as the costof heating is a rincipal item of expenditure in this type of process. Ihave accomplished this principally in two Ways; first, .by reducing themoisture to be evaporated toa minimum; and secondsby evaporating themoisture under conditions most favorable to its carrying its maximumload of nicotine.

One important object in connection with the reduction of the quantity ofmoisture to be evaporated is toevaporate the moisture in suchcircumstances and under such conditions as to increase the carryingcapacity for nicotine vapor, as compared with the carrying capacity ofsteam under the conditions existing in the practice of former processes.More specifically, it has heretofore been considered desirable toevaporate in a partial vacuum, following well-established distilling andevaporating practice, the advantages of. usinga vacuum in the latter artbeing well-established. However,

I have ascertained that while the carrying power of vapor for nicotineis relatively.

y pp y n a small under the vacuum generally employed heretofore, thispower increases markedly as the pressure increases to and aboveatmospheric pressure. I have also ascertained "that the advantagesattendant upon this increased nicotine carrying power more than offsetany possible disadvantages incident upon departure from distillation ina vacuum. An important feature of my invention is, therefore, theemployment in an extraction process of the particular type aboveindicated, of steam at approximately atmospheric pressure for extractingthe nicotine.

Another important object is the evolution of a process in which all themoisture evaporated carries substantially its full load of nicotine.Processes heretofore in general use have employed a substantial quantityof steam in excess of the steam or vapor from the evaporation of thetobacco moisture content with the result that, While the steam firstpassing may carry its full load of nico-- tine, the last of the steamwill carry only a small percentage, or none at all. I have ascertainedthat the carrying capacity of' steam for nicotine vapor atstandard"titer mospheric pressure is approximately 4%; and I employ anamount ofwater, Including that already present in the tobacco material,only slightly in excess of the total necessary to carry off all of thenicotine present in the particular tobacco being treated, the quantityof the nicotine varying with difierent types of tobacco, and beingreadily ascertained by well-known methods. In accomplishing this object,I have found that the amount of water necessary is so small that thetobacco material does not even remotely approach saturation; and suchmaterial, after being treaied with water according to my process. hasthe physlcal a pearance of bein dry or at most on y slightly moist. isphysical condit on of the tobacco is of great advantage in the ratusemployed, and also possesses ot physical and chemical advantages notnecessary to enumerate.

In order to release the nicotine from the acid combinations which holdit in tobacco, it has been the general practice to employ an alkalinesubstance in sufficient quantity to neutralize all the acid elements ofthe tobacco. One principal alkali which has been employed is generallyknown as soda,

particularly in the form known as caustic soda. I have found, however,that the use of soda institutes a large number of secondary chemicalreactions in the tobacco, which generate a more or less gelatinousproduct. This tends to enclose at least part of the nicotine, preventingit from belng carried ofi by the steamfand the ercentage of nicotineremoved is thereby dlminished. I have ascertained that lime issubstantiall superior to soda for this purpose, either 1n the 1form ofmilk of lime or of dry hydrated A further feature of my invention has asits object an improvement in the uniformity and efliciency of action ofthe alkali employed; though this feature is not necessarily dependentupon the employment in the process of the features above set forth. Ihave determined that the alkali is most effective when mixed with thetobacco material in dry powdered form, the water being added after suchintermixture. By this arrangement a much more uniform and effectiveneutralizationof the acids in the tobacco is obtained than where a fluidalkali, such as a soda solution, is applied to the tobacco material asheretofore roposed. This effect is particularly marked when dry hydratedlime is used. I will now set forth the details of the preferred form ofmy process, together with one type of standard commercial apparatus thetobacco. and thereafter mixture, ,while heretofore it has been the whichmay be used in the process. This apparatus is illustrated in thedrawings. which show a somewhat diagrammatic long tudinal verticalsection through a machine of the rotary drum drier type, together withsuitable inlet and outlet connections. The tobacco material should be infinely divided form to permit rapid and thorough pricessing; and should,if necessary, be ground, preferably to a screen having a fi inch mesh.It is then treated with alkali in such a Way that the acids are justneutralized, rendering the material veryslightly alkaline. I havematerially improved this step of the process by mixing a dry finelydivided alkali with mois tening the practice to add the alkali in liquidor solution form. I I have found,that by mixing the alkali in a drystate with the tobacco, I not onl mixing, lint also a higherneutralizing eiiiciency. More accurate measuring of proportions is alsoattained. However, this preferred method of alkaline treatment is notessential to other features of my invention hereinafter set forth.

I therefore prefer to neutralize the acid by adding to the .finelydivided material a suitable quantity of dry powdered alkali, preferablyhydrated lime, and thoroughly point where it will pass a the actiontakes secure a more thorough and rapid.

messes I mix the massin any desired way. The amount of alkali useddepends upon. the

kind oftobacco material processed, the twoimportant factors being theamount of acid 111 the tobacco and its hardness or lmpermca bility, thelatter however being of much less importance than the former.

thoroughly mixed, the proper amount of Water is added. If desired, thewater added may be heated, or may be in the form of steam, reducing theamount of heat necessary to vaporize the water later in the process.these features being controlled largely in commercial considerations,including the type of heating plant employed. In calculating thisamount, the quantity of water already present in thetobacco should. beincluded.

As heretofore indicated, sufficient Water is such that when evaporatedit will he just capable of carrying off all of the nicotine present inthe tobacco. The amount used depends upon the acidity and denseness ofthe tobacco and the amount of nicotine present. A slight exces f wateris also required, as a little water remains in the tobacco afterprocessing under ordinary commercial conditions, and allowance shouldalso be made for ciency. I have found that the most effective extractionis accomplished by employing from 30 to 40% by Weight of water, althougheffective results are obtained with anywhere from 25 to 50% of water. Itis understood that these figures are largely illustrative, as thepercentage of available nicotine in the tobacco is thedeterminingfactor.

Upon the addition of the water the alkali becomes effective toneutralize the acids, and it has been found desirable with the densertypes of tobacco to allow the mixture to stand for a certain period toinsure complete alkaline action. With porous tobaccos place almostimmediately. With the denser tdbaccos a period of about two hours isgenerally sufiicient. Furthermore, the more acid tobaccosrequireslightly more water to expedite the neutralizing action.

I wish-to emphasize the fact that when the proportion of Water indicatedherein is employed, it isabsorbed so, thoroughly by the tobacco that thelatter retains its substantially dry appearance, being at most onlyslightly moist, and it may be handled as a dry substance. It maybe notedthat ordinary tobacco is capable of taking up apfailure to attain fullefiifore reaching complete saturation; .so the difference between theamount of water used in processes employingsaturated tobacco and thatset forth herein will be evident. Such prior processes, because of themuch larger quantity of water employed, involved difiiculties anddisadvantages in the handling of the material, as well as greatlyinferior eflicienc of recovery.

The treated material 1s now subjected to heat suflicient to turn thewater to vapor which carries off the nicotine. This step is carried outin any preferred form of apparatus, preferably of the drier type, whereheat may be efliciently applied and the vapors collected and condensedto recover the nicotine. small amount of water, the quantity of heat reuired is correspondingly small, the vapor belng loaded to full capacitywith nicotine.

, One of themost important features of my process is the elimination ofvaporizationn a yacuurn, heretofore thought necessary 1n this particulartype-of nicotine extraction 7 process. I have found that the carrying capacity of steam for nicotine vapor increases with pressure; and whilesteam at standard Y atmospheric pressure and 212 F. will carryapproximately 4% of vapor, it will carry only about of one per cent ofthe vapor 1n a 25-1nchvacuum. I therefore carry on the vaporization ofthe water at approxi-.'

mately atmospheric pressure, preferably. in a drum type drier or still.This feature also has numerous practical'a-dvantage's, such as theelimination of the vacuum pump and special construction necessary forvacuum systems. Indeed, it may be practicable to carry on this processunder pressures higher thanth at of the atmosphere; butl prefer thelatter, owing to the increased ease with which it maybe carried outunder commercial conditions as compared with either a vacuum or apressure system.

Substantially all of the water employed is vaporized, though underordinary commercial conditions the highest efiiciency is obtained byleaving something less than 5% of moisture in the tobacco. This processmay be carried out in various ways. I have shownin the drawing somewhatdiagrammatically one apparatus suitable .for my purposes, including adrier of the drum type having a horizontal cylindrical body or!- drum 10provided with inletsll having the usual covers, not shown, and outlets12 at the bottom; The material in the drum is agitated by paddles 13mounted on a central 5 sired way, as by-heating fluid in jacket 15,.

shaft 14. The drum 10 is heated in any de- Owing to the relativelyrequiredthe temperature of the tobacco in a typical process of this typerunning from 212 at thestart to about 250 at the close-the heatingoperation for vaporizing the water is much simpler and more eco--nomical than 1n former processes.

For instance, while steam may be employed, either 1 in the drier shownor in others of a similar type, suitably heated oil may be circulatedrough the jacket and paddle shaft, this method being found eflicient andeconomical at the temperatures mentioned.

The tobacco material may be introduced into the drum in various ways. Ihave shown an arrangement in which the various materials used are storedabove the drier, as on the second floor of' a building. They areintroduced through chutes 17 registering with the drum inlets 11; andthe material may either be shoveled into these chutes, or if desiredintroduced automatically. Where the alkali and tobacco are to be mixedin dry form inthe drum itself, the tobacco may be run from bins intochutes 17 through pipes 18, the lime entering through pipes 19. Thedrier may be supported by pillars 20 at a distance above the floorsufficient to allow the discharge of the processed material throughdischarge openings 12 into carriers introduced beneath the drum. In thedrawing 21 designates diagrammatically the first floor ofthe building,and 22 the second floor.-

The Water is contained in tanks 23, and is introduced intothe drierthrough pipes 24, the flow being controlled by cocks 25, so that theamount of water used may be accurately controlled. Forinsuring rapid andeven moistening of the material, steam or air injectors26 may be usedfor introducing the water; and injectors of this type may be employedat. or adjacent the drum openings 11. The latter injectors are wellvpositioned to moisten the center portion of the mix; but when it isdesired to wet-the material as it is inserted in the drum withoutpreliminary agitation in the drier itself. these injectors are properlylocated for the purpose.

With this apparatus, if desired, the dry lime and tobacco material maybe first inserted and thoroughly mixed by the paddles 13. The water maythen be i'njected,.a-nd

the heat is turned on, and the-steam generated will carry off thenicotine through pipes-27, from which they pass to any standard tyne ofcondenser.

While I have shown a single drum 1n which the entire process may becarried out.

with obvious advantages; and while I have indicated that the tobacco andalkali may receive the water, or if desired, the water -'may be appliedwith the lime and tobacco as they are fed into the drum; it may be founddesirable to varythis practice somewhat. For instance, it is highlydesirable to maintain the drier in constant Operation, and

Where the preliminary mixing and ordering steps require time, they maybe carried out separately, either in small mixers adapted for thatpurpose, or by manual labor, suit able bins bein provided in which thetobacco material is allowed to stand after moisture has been applieduntil a sufiicient amount is prepared and is ready for insertion in thedrier. However, it is highly de-- sirable to employ an enclosedcontainer during the neutralizing process, as ammonia fumes are givenofi which are very objectionable. It will be noted that when theneutralizing reaction is taking'place either in the main drum drier orin separate closed mixers, since the fumes are carried on by suitableoutlet pipes, no expensive ventilat ing system for the workroom isrequired as heretofore.

Where the, tobacco carries a high percentage of nicotine it isdesirable, In some instances to subject the tobacco to a succession ofmoistenings, and in order to conserve heat I prefer to remoisten thetobacco by injecting steam into the bottom of the drum as the tobaccodries out. This steam diffuses through the mass of the tobacco, absorbsa certain amount of nicotine, and passes of? to the condenser with themoisture evaporated by the heat of the drum. The result obtained by thusinjecting steam into the drum is similar to what would be Ob-e' tainedif a larger amount of water had been added to the tobacco, but the timeconsumed in the extraction of the nicotine is ver much less. Steam maybe introduced through pipes, such as the injector pipe shown at 26,connected at the bottom of the drum.

The tobacco should be kept slightlv moist until the extraction of thenicotine is completed, since otherwise fine dust may, as the tobaccodries, be carried over to the condenser. For this purpose a measuredamount of water can be admitted to the drum at certain intervals or asmall stream of water can be permitted to fiow into the drumcontinuously. The amount of water should be regulated so that thetobacco is kept slightly moist. When the extraction of the nicotine iscompleted, the water is cut off and the tobacco is completely dried.

While I have indicated the preferred form of my improved process,together with sev-.

- eral lines of variation therein, it will be apparent that numerousother changes and deviations can be made by those skilled in theartwithout departing from the invention as set forth in the followingclaims. Moreover, it will be evident that certain portions ofmy process,such asthe heating at atmospheric pressure and the mixing of the lime indry condition, may be incorporated in other standard processes; and myinvention comprises such use of these features, as indicated in theclaims.

I claim:

1. The processof recovering nicotine from tobacco material, whichconsists in mixing the material with'an alkali, adding moisture to themixture suflicient to hold the nicotine content in solution during theevaporation thereof, but insufiicient to be perceptible, heating themixture to evaporate the moisture, and condensing the vapor.

2. The process of recovering nicotine from tobacco material, whichconsists in mixing the material with an alkali in the dry state, addingmoisture to the mixture sufiicient to hold the nicotine content insolution during the evaporation thereof, but insuflicient to beperceptible, heating the mixture to evaporate the moisture, andcondensing the vapor.

3. The process of recovering nicotine from tobacco material whichconsists in mixing the material with an alkaliand with an amount ofwater suficient to hold the nicotine content of the material insolution, but insufiicient to be perceptible the weight of the totalwater content bein not more than 50% of the Weight of the ing ofi theextracted nicotine, the mixture being at substantially atmosphericpressure when heated,

5. The process of recoverng nicotine from tobacco material whichconsists in mixing thematerial with-a dry alkali and with an amount ofwater substantially equal only to that necessary for generating theminimum quantity of steam capable of extracting and ry tobacco material,and in heating the mixture to vaporice carrying ofi all the nicotinepresent in the tobacco material and in heating the mixture to transformthe water into steam for carrying off the extracted nicotine. 6. Theprocess of recovering nicotine from tobacco material which consists inmixing the material with an alkali, in applying to the mixture while ina closed container an amount of water suficient to hold the nico-.

tine content of the material insolution, but

insufiicient to be perceptible in agitating the adr from finely dividedtobacco material, steps which consist in mixin dry hydrated lime withthe tobacco material, and then adding moisture to the material so mixed.

perceptible ,tureto evol 9.' The process of recov'erin nicotine fromtobacco material which inclu es mixing with the material in finelydivided form a dry alkali, applying thereafter to the material an amountof water sufiicient to raise the water content of the tobacco to a pointonl slightly in excess of the minimum capab e of carrying off thenicotine, and substantially less than the amount required to be andapplying heat to the mixve nicotine-carrying vapors.

. 10. The process of recovering. nicotine from tobacco material whichincludes mixing with the material in finely divided form a dry alkali,applying thereafter to the ma terial an amount of Water sufficient toraise the water content of the tobacco to a point only slightly inexcessof the minimum capable of carrying 0d the nicotine, andsubstantially less than the amount required to be perceptible; andapplying heat to the mixture to evolve nicot ne-carrying vapors,

the mixture being at not substantially less than atmospheric is appliedthereto.

11. The process of recovering nicotine pressure when the. heat fromtobacco material, which consists in adding to the tobacco material aquantity of'moisture less than the absorptlve capacity thereof, heatingto evaporate the moisture, and condensing the vapor.

Signed at Durham in the county ofw Durham and State of N orthiCarolinathis 13th day of February A. D. 1922.

ROBERT B. ARNOLD.

